In a semiconductor integrated circuit, for example, in order to reduce power consumption, a voltage supplied from an external power supply is stepped down by a regulator etc., and an internal circuit is driven by a low voltage. In such a semiconductor integrated circuit, a power-on reset circuit which resets the internal circuit when power is turned on is incorporated in cases.
An integration circuit composed of a resistance and a capacitor is often used for the power-on reset circuit. The integration circuit is connected to a power supply line of an external power supply, and a terminal voltage of the capacitor is output as a power-on reset signal.
In the power-on reset circuit using an integration circuit, in a case that a rise of the external power supply is slow, a time constant of the integration circuit is required to be increased correspondingly. Accordingly, it is necessary to increase a resistance value of the resistance and a capacitance value of the capacitor, resulting in occurrence of a problem that a chip area of a semiconductor integrated circuit is increased.